Methods of assembling fuses



April 3, 1956 P. c. JACOBS, JR., ET AL 2,740,187

METHODS OF ASSEMBLING FUSES Filed March 7, 1955 v E191. I 122/962. la: 54 o 10,

I a T 1a 1, 1a

O I 0 v ma I o I /0 ma E30 0 Fig.9. F

4 O .1 40 O -1 O 40 O .2 70 O 7 0 ma w United States Patent 2,740,187METHODS OF ASSEMBLING FUSES Philip C. Jacobs, Jr., Newtonville, Mass.,and Frederick J. Kozacka, Southa'mton, N. H., assignor's to The Chase-Shawmut Company, Newburyport, Mass.

Application March 7, 1955, Serial No.

6 Claims. (Cl. 29-1555) This invention relates to and more particularlyto assembling of high interrupting complex and costly.

It is, therefore, another object of this invention to provide a methodfor assembling fuses which does not require complex and costly jigs andfixtures.

One problem encountered in assembling high interrupting capacitycurrent-limiting fuses consists the terminal elements thereof exactly ina spaced relation while conductively connecting, e. g. soldering,brazing, the fuse links element's.

casing, reduce the space available therein for accommodating fu'se linksand arc-quenching filler, and are likely to evolve gases under the eatof the arc tending to increase the pressure within the casing incidentto blowing of the fuse.

It is, therefore, another of the terminal elements of the fuse.

It is another object of this invention to provide a method forassembling the fuse structure before the assembly of the same iscompleted.

A still further object of the invention is to provide a novel andminimum with in the speed and the quality of output.

Other objects and advantages of the invention will, in part, be obviousand in part appear hereinafter.

For a more complete understanding of the invention reference may be hadto the following detailed description thereof taken in connection withthe accompanying drawings, in which:

Fig. 1 shows in vertical section the terminal elements of a fuse spacedby a temporary spacer;

Fig. la is a transverse section of the structure shown in Fig. 1 along1a-1a of Fig. 1;

Fig. 2 is a vertical section of the same structure as in Fig. 1 uponaddition of a pair of fuse links;

Fig. 3 is a vertical section of the same structure as in Fig. 2 uponaddition of a casing;

Fig. 4 is a vertical section of the same structure as in Fig. 3 uponremoval of the temporary spacer and plug the holes in the terminalelements;

minal elements;

Fig. 6 shows in vertical section the terminal elements of a fuse spacedby a temporary spacer different from the temporary spacer shown in Fig.1;

Fig. 7 is a vertical section of the same structure as in Fig. 6 uponaddition of a pair of fuse links;

Fig. 8 is a vertical section of the same structure as in Fig. 7 uponaddition of a casing;

Fig. 9 is a vertical section of the same structure as in Fig. 8 uponremoval of the temporary spacer and plugging of one of the holes in theterminal elements; and

' section of the same structure as in the respective face. Beforestarting assembling the constituent parts of the fuse, each of the pairof terminal elements 1 is being provided with a transverse bore 1a.Bores or holes 10 are preferably,

' of terminal blocks or discs 1. In

The casing consists of'a short length of an insulating material havingthe properties required for this type of though not necessarily,-

service such as heat-shock resistance, high-dielectric and burstingstrength, freedom from tracking, etc. In Figs. 3 to 5, inclusive,reference numeral has been applied to indicate the casing of the fuse.Casing 5 is mounted on terminal elements or discs 1 by a relativemovement of the unit shown in Fig. 2 and of casing 5 in a directionlongitudinally thereof. This movement is efiected under considerablepressure, preferably by means of a hydraulic press. Preparatory tomounting of casing 5 upon terminal elements or discs 1, said parts aresuitably arranged in coaxial relttion. Upon mounting of easing 5 uponterminal elements or discs 1, the former is attached to the latter bytransverse steel pins 6, or like fasteners. At this time temporaryspacer 2 may safely be removed from the structure, i. e. pushed out ofholes 1a and taken out of the space bounded bycasing 5 and terminalelements of discs 1, casing 5 having then taken over the function ofsecurely spacing the terminal elements or discs 1. Removal of spacer 2may be effected by placing the semiassembled fuse upon a table having anaperture in registry with holes la and applying pressure upon the top ofspacer 2 by means of a suitable press-operated mandrel. Upon removal ofspacer 2, one of the holes la in one of the terminal elements l is beingclosed, as by a suitable plug 8:: shown 1 in Fig. 4. Thereupon quartzsand or another suitable pulverulent arc-quenching filler is pouredthrough the still open hole 1:: into the'casing of the fuse. When thefuse structure is in part filled with arc-quenching filler, it is placedon a vibrating table and vibrated, which causes the filler to settle.The filling operation may ,then be completed. It may be desirable toalternate several vibrating and refilling operations. When all thepulverulent arc-quenching filler, that is desired to be added, has beenadded, the upper or filling hole la is closed, as by a suitable plug 8bshown in'Fig. 5. The fuse is now completed, except for the addition ofsuitable connectors such as, for instance, blade contacts, for insertingthe fuse into a fuse holder, or equivalent device. The addition of bladecontacts or other connectors has not been illustrated in Figs. 1 to 5,inclusive, the many ways in which this can be achieved being well knownin the art. It is also possible, if desired, to start the process ofassembling the fuse illustrated in Figs. 1 to 5, inclusive, withterminal elements or discs 1 to which a blade contact or other suitableconnector has already been attached.

According to Figs. 6 to 10, illustrating a modification of the processshown in Figs. 1 to 5, terminal elements or discs 10 are provided withlink-receiving grooves on juxtaposed faces thereof. Terminal elements ordiscs 10 are also provided with transverse screw-threaded holes or bores10a. A temporary spacer 20 having screwthreaded axially outer ends isinserted into the screwthreaded holes or bores 10a. The distance betweenterminal elements 10 can be adjusted by rotation of terminal elements 10relative to screw-threaded spacer stud 20. The friction between the malescrew-threads on spacer stud or spacer post 21 and female screw-threadsin bores 10a is sufiiciently high to preclude accidental rotation ofterminal elements 10 with regard to post or stud 20. Upon proper spacingof terminal elements 10 the fuse links are inserted into thelink-receiving grooves 30, as shown in Fig. 7. After establishing lowresistance current carrying joints between the ends of links it? andterminal elements 10, casing is mounted under pressure upon the latter,as shown in Fig. 8. Thereafter the transverse steel pins are beingdriven through casing 50 into terminal elements 10, which enables thesubsequent removal of temporary screw-threaded spacer 29. Fig. 9 showsthe structure upon removal of screw-threaded spacer 20 and closing ofthe lower screw-threaded opening 10a by means of a plug a in the processof being filled with a pulverulent arc-quenching filler 70. The fusestructure is then subjected to vibrations and gradually filled to fullcapacity, whereupon it is closed by inserting the upper screw-threadedplug 80b into the upper screw- 4 threaded hole 10a. Any kind ofconnectors may then be added to the fuse such as, for instance, bladecontacts or stud contacts (not shown).

It will be understood that although but two methods illustrating theinvention have been described in detail, the invention is not limitedthereto. It will also be understood that the methds illustrated may bemodified without departing from the spirit and scope of the invention asset forth in the accompanying claims.

It is claimed:

1. A method of assembling electric fuses comprising the steps ofproviding each of a pair of terminal elements with a transverse hole, ofarranging said pair of elementsin spaced relation with said hole in eachof said pair of elements in registry, of inserting a spacer intosaid'hole in each of said pair of elements to maintain said pair ofelements in spaced relation, of conductively interconnecting said pairof elements by fuse link means, of mounting a casing upon said pair ofelements, of attaching said casing to said pair of elements, and ofremoving said spacer from said hole in each of said pair of elements andfrom the space bounded by said pair of elements and said casing.

2. A method of assembling electric fuses comprising the steps ofproviding a pair of terminal elements with transverse holes, ofarranging said pair of terminal elements in spaced relation with saidholes thereof in alignment, of inserting spacing means into said holesto maintain said pair of terminal elements in spaced relation, ofconductively interconnecting said pair of terminal elements by fuse linkmeans, of mounting a casing upon said pair of terminal elements, ofattaching said casing to said pair of terminal elements, of removingsaid spacing means from said holes and from the space bounded by saidpair of terminal elements and said casing, and of closing said holes.

3. A method of assembling electric fuses comprising the steps ofproviding each of a pair of terminal elements with a transverse hole, ofarranging said pair of elements in spaced relation with said hole ineach in alignment, of inserting a spacer into said hole in each of saidpair of elements to maintain said pair of elements in spaced relation,of conductively interconnecting said pair of elements by fuse linkmeans, of pressure-mounting a casing upon said pair of elements, ofattaching said casing to said pair of elements, of removing said spacerfrom said hole in each of said pair of elements and from the spacebounded by said pair of elements and said casing, of filling apulverulent arc-quenching filler into said casing through said hole inone of said pair of said hole in said'one of said pair of elements.

4. A method of assembling electric fuses comprising the steps ofproviding a pair of terminal elements with transverse holes, ofarranging said pair of terminal elements in spaced relation with saidholes thereof in alignment, of inserting spacer 'means into said holesto maintain said pair of terminal elements in spaced relation, ofconductively interconnecting said pair of terminal elements by fuse linkmeans, of pressure-mounting a casing upon said pair of terminalelements, of pinning said casing to said pair of terminal elements, ofremoving said spacer means from said holes and from the space bounded bysaid pair of terminal elements and said casing, of filling a pulverulentarc-quenching filler through one of said holes into said casing, and ofsealing said one of said holes.

5. A method of assembling electric fuses comprising the steps ofproviding each of a pair of terminal elements with a central transversebore, of arranging said pair of terminal elements in spaced relationwith said bore in each of said pair of terminal elements in registry, ofpress-fitting a center post into said bore in each of said pair ofterminal elements to frictionally maintain said pair of terminalelements in spaced relation, of conductively interconnecting said pairof terminal elements by fuse elements, and of plugging link means, ofpressure-mounting a casing upon said pair of terminal elements, ofattaching said casing to said pair of terminal elements, and of removingsaid center post through said bore in one of said pair of terminalelements from said pair of terminal elements and from the space boundedby said pair of terminal elements and by said casing.

6. A method of assembling electric fuses comprising the steps ofproviding each of a pair of terminal elements with a central transversescrew-threaded bore, of arranging said pair of terminal elements inspaced relation with said bore in each of said pair of terminal elements10 pair of terminal elements and by said casing.

No references cited.

